It took nearly a year to bring charges against Pimentel and the investigation began just weeks after the arrest of another Los Angeles elementary school teacher, Mark Berndt, who has pleaded not guilty to 23 counts of lewd conduct involving students.

Following that scandal, the district mandated that parents be notified within 72 hours of a report of a suspected abuser, and that each case be reviewed by several human resources staffers to ensure it is reported to the Commission on Teacher Credentialing.

District officials vowed to investigate molestation claims and move quickly to remove suspected teachers from classrooms while investigations are ongoing which apparently occurred in Pimentel’s case.

Police were contacted in March by the parents of five students who said Pimentel had touched their children inappropriately. District officials immediately removed him from campus and notifications were sent out.

More than 70 interviews were conducted during the police investigation, and 20 female students were found to have been victimized, Los Angeles police Capt. Fabian Lizarraga said. Another victim was a female teacher who complained that Pimentel had inappropriately touched her, police said.

The alleged abuse occurred in Pimentel’s fourth-grade classroom during school hours and in some cases was witnessed by other students, Lizarraga said. The sexual abuse involved fondling over and underneath clothing, he said.

The Pimentel case may have been the first in the district that fell under the new policy, district Superintendent John Deasy said.

“It was very close to the first, if not the first,” he said. “I don’t know if it was a direct result (of the Miramonte case). There was a potentially serious problem there and we acted and did what we did.”

Lizarraga added that although there was a spike in parent complaints after the Miramonte case, there wasn’t any tie to the Pimentel case.

“These were some really alert parents knowing their kids and noticing subtle changes in their personalities,” Lizarraga said.

The accusations against Pimentel span eight months, dating back to September 2011.

In a separate case, a jury in December ordered the district to pay a boy molested by an elementary school teacher $6.9 million – among the largest awards in the history of the school system. The jury found the district liable for the repeated molestation of the 10-year-old student in 2008 and 2009 by teacher Forrest Stobbe at Queen Anne Elementary School in the city’s mid-Wilshire district.

A previous report of sexual misconduct against Pimentel occurred four years ago at the school, and another complaint was made eight years ago at another elementary school where both a female principal and Pimentel had worked, Deasy said.

“My determination was that she was previously mishandling other complaints,” Deasy said. “My intent was to fire them.”

The district never got the chance because both Pimentel and the principal retired after the allegations surfaced last March.

“You can’t fire someone who doesn’t work for you,” Deasy said.

Police said they will review the principal’s failure to report those previous allegations.

Investigators attempted to interview Pimentel last year but he declined.